Monitoring Breeding Performance of the Black-tailed Gull <i>Larus crassirostris</i> on Kabushima Island, Japan, from 2012 to 2016

We monitored the breeding performance of Black-tailed Gulls Larus crassirostris on Kabushima Island from 2012 to 2016. During this period mean clutch sizes and productivity ranged from 1.57 to 2.16, and 0.03 to 0.29, respectively. The mean clutch size from 2014 to 2016 was higher than in 2012 and 2013, but the productivity from 2014 and 2016 was lower than in 2012 and 2013.